Pulsed excimer laser deposition of ferroelectric thin films

Abstract

Pulsed UV excimer laser ablation was employed to deposit multi-axial, bi-axial and uni-axial ferroelectric compositions of PZT, bismuth titanate and lead germanate respectively. In general, a fluence lower than 2 J/cm² caused a preferential evaporation of volatile components, resulting in stoichiometric imbalance. However, the fluences beyond 2 J/cm² enabled the deposition of stoichiometric thin films of multi-component oxide systems. The intrinsic bombardment due to the energetic ablated species during the thin film deposition seemed to influence the composition, structure, orientation and the electrical properties. The electrical characterization of ferroelectric films indicated a dielectric constant of 800–1000, a P_r of 32μC/cm² and E_c of 130KV/cm for polycrystalline PZT films and the corresponding quantities were measured to be 150, 7 μC/cm² and 20 KV/cm for in-situ crystallized c-axis preferred oriented bismuth titanate films. Lead germanate thin films oriented along c-axis (003) showed a dielectric constant of 30, a P_r of 2.5 μC/cm² and E_c of 55 KV/cm.